import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int x = sc.nextInt();
    int y = sc.nextInt();
    int l = sc.nextInt();
    int ans = (Math.abs(x) + l - 1) / l + (Math.abs(y) + l - 1) / l;
    if(y < 0) {
      ans += 2;
    } else if(x != 0) {
      ans += 1;
    }
    System.out.println(ans);
  }
}